% 计算信道方向角Theta
function Theta = calculateTheta(p_i_l, p)
    delta_x = p(1) - p_i_l(1);
    delta_y = p(2) - p_i_l(2);
    delta_z = p(3) - p_i_l(3);
%     Theta = atan2(delta_x, sqrt(delta_y^2 + delta_z^2)); 
%     Theta = atan2(delta_y, sqrt(delta_x^2 + delta_z^2)); 
    Theta = atan2(delta_z, sqrt(delta_x^2 + delta_y^2));     
end
